[sanddrag]

I would leave it 1/8" in the areas where the cutouts for wheels and pillow blocks are, but still, is that enough? As for the rest of it, should I leave it solid .090 or .125 with holes/cutouts? I'm thinking solid .090 is better.

Anyway, as for the critical area like where the wheel goes, it is possible I could start with .25 wall tubing and take it down to .1875 wall in that area, and then .090 or .125 on the rest. But that is a lot of material waste.

You are all probably thinking "but you aren't going to get the same outside dimension. Anyway, I know, and I don't really care. All I care about is the rough outside diemnsion of 2.5" sq and making it less than 1 lb per foot.